1. Field of the Invention
The present invention generally relates to charging of batteries and, more particularly, is concerned with an improved battery charger with timer-controlled charging, shut-off and reset operations.
2. Description of the Prior Art
Equipment, such as electric golf carts and the like, are typically placed in storage for extended periods of time, such as during offseason, when not in use. A battery provided on an electric golf cart will deteriorate significantly in its ability to hold charge if not kept at full charge while in storage and not being used. Such deterioration can lead to shortening of the useful life of the battery.
In order to avoid the aforementioned adverse affects, a widespread conventional practice is to provide a battery charger on the electric golf cart which is semi-automatic in that it will charge the battery, sense the charge condition of the battery, and then turn itself off when fully charged. Typically, such semi-automatic battery charger has a charging circuit, a pair of lead wires for connection to the respective positive and negative terminals of the battery, a control circuit, and a main relay having a switch portion and an actuator portion. The switch portion of the main relay is connected between the source of electrical power and the charging circuit. The actuator portion of the main relay is connected between ground potential and the output of the control circuit. The input of the control circuit is connected to the hot or positive terminal of the battery via one of the respective lead wires of the charger. The switch of the main relay normally assumes an open circuit condition when the lead wires are not connected to the battery terminals. Upon connecting the lead wires to the battery terminals, the actuator portion of the main relay is supplied with electrical power from the battery and causes the switch portion thereof to change from the open circuit condition to a closed circuit condition permitting electrical power to flow to the charging circuit of the charger from the power source.
The control circuit of the battery charger has a sensor which detects the magnitude of the voltage across the battery terminals. As the charging circuit operates to charge the battery, the magnitude of the voltage across the battery terminals is fed back to and detected by the sensor in the control circuit so that a determination can be made as to how much charge is still needed for the battery. When the feedback voltage is of sufficient magnitude to indicate to the control circuit that the battery is fully charged, the control circuit will then terminate operation of the charging circuit and thus charging of the battery by the charger by cutting off electrical power to the main relay. Once charging is so terminated and the battery charger is, in effect, shut or turned off, the charger cannot be turned on again until after the control circuit is reset which can only occur by disconnecting the lead wires from the battery terminals or interrupting the feedback voltage.
A drawback of this semi-automatic mode of operation of a typical conventional battery charger is that a person has to be available to monitor the charging operation in order to initiate a subsequent charging cycle. The person has to physically disconnect and reconnect the lead wires of the charger from and to the battery terminals or to interrupt the feedback voltage from the battery to the charger control circuit in some manner in order to cause resetting of the charger control circuit which will thereafter permit the charger to initate another charging cycle.
Consequently, a need still exists for improvement of the semi-automatic battery charger so as to achieve periodic unattended recharging of a battery and thereby overcome the drawback of the prior art.